A press device for pressing the slider by motors, which are a plurality of driving sources, is known, and the applicant filed a patent application as the Patent Document 1.
FIG. 7 shows a conventional publicly known press device. FIG. 7 is substantially the same as that disclosed in the Patent Document 1.
In FIG. 7, in a frame body 404 formed by a base 401, a support plate 402 and a plurality of guide poles 403, two sliders 405 and 406 are provided, and at the four corners of each of the sliders 405 and 406, sliding holes engaged with the guide poles 403 and through which the sliders 405 and 406 freely slide respectively in the axial direction of the guide poles 403 are provided.
On an upper face of the support plate 402, a plurality of, four in this case, for example, mounting bases 408 are provided, and a servo motor 409 for rapid traverse containing an encoder is mounted on each of the mounting bases 408.
Since the constitution and components relating to each of the servo motors 409 for rapid traverse mounted on the four mounting bases 408, which will be described below, are totally the same, only one of them will be described.
A screw shaft 410 fastened to a shaft of the servo motor 409 for rapid traverse inside the mounting base 408 is pivotally supported by the support plate 402 capable of rotation, screwed with a screw feed nut 411 fixed to the slider 406 and can penetrate the slider 405 provided further below the slider 406. Therefore, the slider 406 is raised or lowered by synchronized normal/reverse rotation of the four servo motors 409 for rapid traverse, and the slider 406 can be reciprocated by rotation control of the servo motors 409 for rapid traverse.
On the slider 406, a double-nut lock mechanism 414 for clamping, that is, fixing the screw shaft 410 onto the slider 406 is provided. When this lock mechanism 414 is operated, the screw shaft 410 is fixed (locked) onto the slider 406 and the screw shaft 410 and the slider 406 are integrated so that the screw shaft 410 and the slider 406 can not mutually move.
On an upper face of the slider 406, a plurality of, 2, 3 or 4, for example, mounting bases 415 are provided, and a servo motor 417 for pressurization containing an encoder and having a reducer 416 is mounted on each of the mounting bases 415. Since the constitution and the components of each of the servo motors 417 for pressurization mounted on the mounting base 415 are totally the same, only one of them will be described below.
A ball screw shaft 418 fastened to a shaft of the servo motor 417 for pressurization inside the mounting base 415 is screwed with a ball screw mechanism 419 with differential mechanism in which a ball and a nut member are provided inside, and pivotally supported by the slider 406 capable of rotation. The ball screw shaft 418 and the ball screw mechanism 419 with differential mechanism fixed on the upper face of the slider 405 form the structure in which the two sliders 406 and 405 are connected. That is, by rotating the plurality of servo motors 417 for pressurization provided on the mounting bases 415 in normal or reverse rotation in synchronization, the slider 405 is raised or lowered, and the slider 405 can be reciprocated by rotation control of the servo motor 417 for pressurization.
On a lower end face of the slider 405, an upper die 407 is mounted, while a lower die 420 is provided on the base 401 at a position corresponding to this upper die 407. And between the base 401 and the support plate 402, a pulse scale 421 for detecting a position of the slider 405 is mounted along each of the four guide poles 403, respectively, to detect a contact position between the upper die 407 and a work piece 422 loaded on the lower die 420 and an upper limit standby position and a lower limit lowering position of the upper die 407. Parallel control of the slider 405 or the like is performed based on the four pulse scales 421.
A control device 423 for controlling rotation of 2 to 4 servo motors 409 for rapid traverse and 2 to 4 servo motors 417 for pressurization and for controlling the lock mechanism 414 for fixing (locking) the screw shaft 410 onto the slider 406 or releasing (unlocking) the same receives various set values inputted in advance and position signals detected by the pulse scales 421 for detecting a position of the slider 405, that is, the position of the upper die 407. And the control device 423 rapidly lowers the upper die 407 through the slider 406 lowered by rotation of the screw shaft 410 by the servo motor 409 for rapid traverse and the slider 405 lowered by rotation of the servo motor 417 for pressurization, when necessary, till the time when the upper die 407 located at the upper limit standby position is brought into contact with the work piece 422 loaded on the lower die 420 or at the time immediately before the contact. After stop of the servo motor 409 for rapid traverse, the lock mechanism 414 is immediately locked and from the time when the upper die 407 is brought into contact with the work piece 422 or the time immediately before the contact to the time when the upper die 407 is lowered to a predetermined lower limit lowered position (an imaginary line position (407) of the upper die 407 in FIG. 7), the upper die 407 is lowered by the servo motor 417 for pressurization. That is, the slider 405 is decelerated as compared with the rapid lowering speed. In this case, the control device 423 brings the servo motor 417 for pressurization in the torque applied mode so that the upper die 407 presses the work piece 422 loaded on the lower die 420 so as to press the work piece 422 into a predetermined shape. After the upper die 407 reaches the lower limit lowered position, lock of the lock mechanism 414 is released (unlocked), and such control is performed that the upper die 407 is rapidly raised using both raising of the slider 405 by the servo motor 417 for pressurization and raising of the slider 406 by the servo motor 409 for rapid traverse.
After stop of the servo motor 409 for rapid traverse, the lock mechanism 414 is locked and the screw shaft 410 is fixed (locked) onto the slider 406. The lock mechanism 414 works as follows. Even if a force operates to move the slider 406 upward through the slider 405, the ball screw mechanism 419 with differential mechanism and the ball screw shaft 418 by reaction generated when the upper die 407 presses the work piece 422 loaded on the lower die 420, the rotation of the screw shaft 410 is able to be prevented by the above described integration of the screw shaft 410 and the slider 406 and then the slider 406 is not able to move upward but maintains the stop position. That is, the upper die 407 can apply a predetermined press load onto the work piece 422.
FIG. 8 shows an enlarged explanatory view of a preferred embodiment of a moving mechanism portion of the upper die with regard to a variation of an electric press machine corresponding to FIG. 7, and the same components as those in FIG. 7 are given the same reference numerals. Also, FIG. 8 is substantially the same as that disclosed in the Patent Document 1.
In FIG. 8, inside the frame body 404 formed by the base, not shown, the support plate 402 and the plurality of guide poles 403, a slider 460 is provided, and at four corners of the slider 460, sliding holes engaged with the guide poles 403 and through which the sliders 460 freely slide in the axial direction of the guide poles 403 are provided, respectively.
On the upper face of the support plate 402, a plurality of, two or four, for example, mounting bases 461 are provided, and the servo motor 409 for rapid traverse containing an encoder is mounted on each of the mounting bases 461 through the reducer 416 (the reducer 416 may be omitted).
Since the constitution and components relating to each of the servo motors 409 for rapid traverse mounted on the plurality of mounting bases 461, which will be described below, are totally the same, only one of them will be described.
An output shaft 462 of the servo motor 409 for rapid traverse penetrating the mounting base 461 mounted on an upper face of the support plate 402 is connected to the tip end of a ball screw shaft 463 through a coupling 464. At a hole 465 provided on the support plate 402, a bearing 467 fitted in the ball screw shaft 463 through a bearing holder 466 is mounted, and the ball screw shaft 463 driven by the servo motor 409 for rapid traverse is mounted onto the support plate 402 capable of rotation.
On the support plate 402, a lock mechanism 468 is provided. This lock mechanism 468 is comprised by a gear 439 fixed to the ball screw shaft 463 and a solenoid 440 having a gear piece 441 meshed with the gear 439. When this lock mechanism 468 is operated, the gear piece 441 is meshed with a tooth of the gear 439, the ball screw shaft 463 is fixed to the support plate 402, and the ball screw shaft 463 is integrated with the support plate 402 so that the ball screw shaft 463 can not be rotated any more.
On an upper face of the slider 460, a support body 470 with a hollow 469 inside is fastened. At the hollow 469 of this support body 470, a hole 473 at the center capable of free rotation of the ball screw shaft 463 together with a hole (not shown) provided at the slider 460, a worm wheel 476 supported by an upper and a lower bearings 474 and 475 for thrust load and rotatably supported around the ball screw shaft 463 as a center shaft, and a servo motor 478 for pressurization containing an encoder to which a worm 477 meshed with the worm wheel 476 is fixed are provided. At an upper portion of the worm wheel 476, a ball screw mechanism 479 provided with a ball and a nut member inside to screw with the ball screw shaft 463 is fixed capable of rotation in the form projecting to a ceiling portion of the support body 470.
When the servo motor 478 for pressurization is stopped, mesh between the worm 477 fixed to the output shaft of the servo motor 478 for pressurization and the worm wheel 476 makes the ball screw mechanism 479 fixed at the upper portion of the worm wheel 476 to be integrated with the slider 460. Then, the ball screw shaft 463 is driven by normal rotation/reverse rotation of the servo motor 409 for rapid traverse, the slider 460 is raised or lowered through a connecting mechanism (third connecting mechanism) 471 constituted by the ball screw mechanism 479 screwed with the ball screw shaft 463, the worm wheel 476, the two bearings 474 and 475, the support body 470 or the like, and the slider 460 can be reciprocated by rotation control of the servo motor 409 for rapid traverse.
Also, when the servo motor 478 for pressurization is rotated in the normal/reverse direction in the state where the lock mechanism 468 is operated and the ball screw shaft 463 and the support plate 402 are integrated, a rotation portion constituted by the worm wheel 476 and the ball screw mechanism 479 is rotated through the ball screw shaft 463 in the stationary state, and the slider 460 is raised or lowered. That is, the slider 460 can be reciprocated by rotation control of the servo motor 478 for pressurization.
After the servo motor 409 for rapid traverse is stopped, the lock mechanism 468 is locked and the ball screw shaft 463 is fixed to the support plate 402. This reason is as follows. That is, an unwanted action operates so as to move the slider 460 upward and then to rotate the ball screw shaft 463 by reaction generated when the upper die 407 presses the work piece 422 loaded on the lower die 420. In this invention, even if the unwanted action to move the slider 460 upward tries to rotate the ball screw shaft 463, the ball screw shaft 463 and the support plate 402 are integrated as above, then the ball screw shaft 463 is prevented from being rotated. Thus, the upper die 407 can apply a predetermined press load onto the work piece 422.
Though not shown, the upper die 407 (See FIG. 7) is mounted on a lower end face of the slider 460, and a lower die 420 (See FIG. 7) is provided on the base 401 (See FIG. 7) at a position corresponding to the upper die 407. And between the base 401 and the support plate 402, the pulse scale 421 for detecting a position of the slider 460 is provided along each of the four guide poles 403 to detect a position of contact between the upper die 407 and the work piece 422 (See FIG. 7) loaded the lower die 420 as well as an upper limit standby position and a lower limit lowered position of the upper die 407.
A control device 480 for controlling rotation of each of the servo motors 409 for rapid traverse and the servo motors 478 for pressurization and the lock mechanism 468 for fixing (locking) the ball screw shaft 463 onto the support 402 or releasing (unlocking) the same receives various set values inputted in advance and position signals detected by the pulse scales 421 for detecting a position of the slider 460, that is, the position of the upper die 407. And the control device 480 rapidly lowers the upper die 407 through the rotation of the ball screw shaft 463 by the servo motor 409 for rapid traverse and the rotation of the rotation portion of the connecting mechanism 471 by the servo motor 478 for pressurization, when necessary, till the time immediately before the upper die 407 located at the upper limit standby position is brought into contact with the work piece 422 loaded on the lower die 420. After stop of the servo motor 409 for rapid traverse, the lock mechanism 468 is immediately locked so that the support plate 402 and the ball screw shaft 463 are fixed, and from the time the upper die 407 is brought into contact with the work piece 422 or the time immediately before the contact till the upper die 407 is lowered to a predetermined lower limit lowered position (the imaginary line position (407) of the upper die 407 in FIG. 7), the upper die 407 is lowered through the slider 460 by rotation of the rotation portion of the connecting mechanism 471 under fixation between the support plate 402 and the ball screw shaft 463 at a speed slower than the above rapid lowering speed. In this case, the control device 480 brings the servo motor 478 for pressurization in the torque applied mode under the fixation between the support plate 402 and the ball screw shaft 463 so that the upper die 407 presses the work piece 422 loaded on the lower die 420 so as to press the work piece 422 into a predetermined shape. After the upper die 407 reaches the lower limit lowered position, lock of the lock mechanism 468 is released, and such control is performed that the upper die 407 is rapidly raised to the original upper limit standby position through the slider 460 using both the servo motor 409 for rapid traverse and the servo motor 478 for pressurization under release of fixation between the support plate 402 and the ball screw shaft 463.
The internal structure of the nut member of the ball screw shaft 479 is, as shown in FIG. 8, a ball arranged in a ball groove of the ball shaft screw 463 is circulated from a lower ball groove to an upper ball groove by rotation of the ball screw shaft 463 and the ball screw mechanism 479, and by this circulation of the ball, locally concentrated abrasion of the ball can be avoided.
Also, since ball-bearing position adjusting means 481 is provided between the slider 460 and a base disk 482, a differential member 453 is moved in the right and left directions in the drawing by rotating a screw portion 457. Therefore, a nut member of the ball screw mechanism 479 is moved through the base disk 482 on which the support body 470 is mounted for an extremely short distance in the perpendicular direction. By this, the ball groove in the nut member of the ball screw mechanism 479 changes its position in contact with the ball arranged in the ball groove in the ball screw shaft 463 at loading of the press working, that is, the position of the ball groove in contact with the ball in the nut member of the ball screw mechanism 479 is changed at loading of the press working, and durability of the nut member of the ball screw mechanism 479 is ensured as compared with the constitution that the ball is brought into contact with the same position every time.
In the press device as shown in FIGS. 7 and 8, the control device 423 (or 480) performs driving control for the servo motor 409 for rapid traverse and the servo motor 417 (or 478) for pressurization in press working.
FIG. 9 shows a block diagram for driving control for the servo motor for rapid traverse and the servo motor for pressurization. It is to be noted that FIG. 9 shows a block diagram of only one pair of the servo motor for rapid traverse and the servo motor for pressurization, but it may be considered that the similar control is performed for each of plural pairs.
Reference numeral 101 in FIG. 9 is a time/position pattern generation portion for generating information specifying the position that the slider should take according to time when the press working progresses (corresponding to individual time). And reference numerals 111 and 121 show servo modules for position loop, respectively, while reference numerals 112 and 122 for servo modules for speed loop, respectively.
Moreover, reference numeral 113 is an inertia moment response portion corresponding to the servo motor for rapid traverse for outputting an angular speed of the servo motor for rapid traverse. Reference numeral 123 is an inertia moment response portion corresponding to the servo motor for pressurization. Furthermore, reference numerals 114 and 124 are integration response portions corresponding to integration of an inputted angular speed, and in an example shown in FIG. 7 or 8, it may be considered as an output from the pulse scales 421 representing an actual position of the slider. Also, reference numerals 115, 116, 117, 125, 126 and 127 denote adders, respectively.
According to the time when press working progresses (corresponding to individual time), a signal of position that the slider should take is generated by an NC device, not shown, for example. That is, it is supplied to the servo modules 111 and 121 for position loop. In the adders 115 and 125, a deviation between the position signal which should be taken and an actual position signal of the slider is acquired, and the deviation is inputted into the servo modules 111 and 121 for position loop. The servo modules 111 and 121 for position loop issue velocity signals corresponding to the servo motor for rapid traverse and the servo motor for pressurization, respectively.
The adders 116 and 126 acquire deviation between the respective velocity signals and actual angular speed signal of the servo motor for rapid traverse and the servo motor for pressurization, which are supplied to the servo modules 112 and 122 for speed loop, respectively. And they become signals dealing with disturbance generated in some cases at the adders 117 and 127 and drive the servo motor for rapid traverse and the servo motor for pressurization.
In the case shown in FIG. 9, so-called feedback control is performed that the deviation between the signal position which should be taken by the slider and the actual signal position of the slider is acquired particularly at the adders 115 and 125. Though not shown, if plural pairs of motors for vertically moving the slider exist as shown in FIG. 7 or 8, control according to the block diagram corresponding to one pair of motors as shown in FIG. 9 is performed to each of the plural pairs. And such control is performed that the slider is correctly and horizontally (without being tilted) lowered during press working by the plural pairs of motors.
Patent Document 1: Unexamined Japanese Patent Application (Kokai) No. 2004-358525